# Compressor Anti Surge Config from CCC

#### Andrej

Hi Guys!!!

At this moment I'm analyzing a Configuration Software from CCC for a certain compressor. There is one point, which is not clear for me. I now, how CCC calculates the PVs in their system: PV = Gain*SV + Bias. I can accept this calculation for all inputs exept of the flow measurement. For my understanding, for the flow the Gain is equal to 1 and Bias is 0. But, in my configuration the Gain is equal to 0.5. Can somebody explain me, why this factor is chosen for the flow measurement?

Regards Andrej

#### ControlsGuy25

Hi Guys!!!

At this moment I'm analyzing a Configuration Software from CCC for a certain compressor. There is one point, which is not clear for me. I now, how CCC calculates the PVs in their system: PV = Gain*SV + Bias. I can accept this calculation for all inputs exept of the flow measurement. For my understanding, for the flow the Gain is equal to 1 and Bias is 0. But, in my configuration the Gain is equal to 0.5. Can somebody explain me, why this factor is chosen for the flow measurement?

Regards Andrej
Hi!

I have read a CCC manual it is showing a "gains & biases chart" on DIFFERENT parameters like flow, pd ( abs ) pd (gauge) ...

Plz have a good read on that OEM manual...

there is also tranmitter span to take into account when calculating flow...

I attach the document here so you can read it and tell us your feedback ..

James

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#### ControlsGuy25

It is a very good support for solving this case...

#### Andrej

Hi!

Thank you for your quick response!!! I also have read this manual before I decided to post my question in this forum.
But, I still can't understand, how for the differential pressure you can get a Gain, which is unequal 1. I can understand the calculation, which is shown in the document, for all Temperature and Pressure measurement on the compressor.
The Gain, in my case 0.5, for the flow device doesn't look logical for me.

#### ControlsGuy25

Hi!

Thank you for your quick response!!! I also have read this manual before I decided to post my question in this forum.
But, I still can't understand, how for the differential pressure you can get a Gain, which is unequal 1. I can understand the calculation, which is shown in the document, for all Temperature and Pressure measurement on the compressor.
The Gain, in my case 0.5, for the flow device doesn't look logical for me.
Hi

A sketch/drawing and formulas presentation would be greatly welcomed here prior to give you any notes...

#### Andrej

Hi

A sketch/drawing and formulas presentation would be greatly welcomed here prior to give you any notes...

I have put the different equations (extraction from the document you forwarded me to) for calculation:
- dP
- Pd
- Td

In my case I have Pd (Discharge Pressure) Measurement in Gauge, Td (Discharge Temperature) Measurement and dP (Orifice Plate) on the compressor output side.
The use of these equations in my situation is shown below:

dp: Gain = 1,0
dp: Bias = 0

Pd (gauge): Gain = Pd,span/(Pd, span+Patm) =20/(20+1,013) = 0,95179
Pd (gauge): Bias = Patm/(Pd,span+Patm) = 1,013/(20+1,013) = 0,0482

Td: Gain = Td,span/(Td,span+273,15) = 200/(200+273,15) = 0,4227
Td: Bias = 273,15/(Td,span+273,15) = 0,5773

The gain and bias for suction pressure and suction temperature has been calclulated accordanly to the other equations.

Then I have compared my calculation with the configuration of CCC controller. Everything is matching exept of the dp. The CCC configuration shows a value for the Gain, which is 0.5.

And exacly this I can't understand, why. For the differential measurement I don't need to take the correction, which is needed for Pressures and Temperatures, into account.

Can somebody explain, what else needs to be considered for the Gain definition for dP-(Orifice Plate)-measurement in CCC?

#### ControlsGuy25

Have a read on page 54 on this document that i shared here...

It is explaining minimum flow control (mode fd32) ...it can englight some points that you mentionned on your posts

The document does not mentionning anything on orifice plate measurement in CCC..

#### ControlsGuy25

Can the original poster provide a feedback...thx

#### Andrej

Can the original poster provide a feedback...thx
Yes, I have read the manual and checked the original configuration with the help of different calculations, which are provided in the manual. But, unfortenatelly I was not able to reproduce the values from the config file.
So, at the moment I am not following the problem any more.